JP2012047298A - Hydraulic drive device of hydraulic work machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily change the drive/brake pressure of a hydraulic swing motor while leaving the structure of a shock-less function as it is, and to change the maximum drive torque and brake torque of the hydraulic swing motor.SOLUTION: In a swing motor unit 4, there are arranged first swing relief valves 44a, 44b having the shock-less functions which limit the drive/brake pressure of the hydraulic swing motor 40 so as not to exceed first set pressure, and second swing relief valves 46a, 46b which limit the drive/brake pressure of the hydraulic swing motor so as not to exceed second set pressure. By switching valves 47a, 47b by operating a relief-pressure change command switch 8, there is selected one of a mode at which the relief characteristic of the first swing relief valve is made effective as it is, and a mode at which there can be obtained a relief characteristic at which the first set pressure of the relief characteristic of the first switch relief valve is lowered to the second set pressure of the second swing relief valve.

Description

  The present invention relates to a hydraulic drive device that is provided in a hydraulic working machine such as a hydraulic excavator and makes a relief pressure of a hydraulic swing motor that drives a swing body variable.

  A hydraulic drive device for a hydraulic working machine having a swinging body such as a hydraulic excavator includes a swing motor unit that incorporates a hydraulic swing motor that drives the swinging body. In the swing motor unit, there is a relief valve called an overload relief valve that limits the pressure of the pressure oil supplied to the hydraulic swing motor or the pressure oil discharged from the swing motor so as not to exceed a predetermined pressure. Has been.

  As a relief valve of a hydraulic swing motor, a relief valve having a shockless function is known as described in Patent Document 1 in order to reduce a shock at the time of turning start or stop of turning.

  Further, as described in Patent Document 2, there is known a hydraulic drive device that can change a set pressure (relief pressure) of a relief valve of a hydraulic swing motor. By making the relief pressure changeable, the drive pressure or braking pressure of the hydraulic swing motor can be changed, and the maximum drive torque or braking torque of the hydraulic swing motor can be changed. In Patent Document 2, by changing the set pressure of the relief valve according to the attitude of the front working machine, the maximum drive torque or braking of the hydraulic turning motor is changed according to the change in the inertial mass of the upper turning body that changes according to the attitude of the front working machine. The torque has been changed to improve the operability.

Japanese Utility Model Publication No. 5-6266 JP-A-6-173299

  As described above, as described in Patent Document 1, a relief valve having a shockless function is known. In Cited Document 2, a set pressure (relief pressure) of a relief valve of a hydraulic swing motor can be changed. . In this case, the relief valve of the hydraulic swing motor has a shockless function as described in Patent Document 1, and as described in Patent Document 2, the set pressure (relief pressure) of the relief valve of the hydraulic swing motor is set. If the change can be made, it is possible to obtain both effects of reducing the shock at the time of turning start or stop by the shockless function of the relief valve and changing the maximum driving torque or the braking torque of the hydraulic turning motor.

  However, making a relief valve having a shockless function into a variable relief type requires a very complicated mechanism and is difficult to realize both in terms of structure and price.

  An object of the present invention is to make it possible to easily change the driving pressure or braking pressure of a hydraulic swing motor while maintaining the structure of a relief valve having a shockless function, and to change the maximum driving torque or braking torque of the hydraulic swing motor. It is an object of the present invention to provide a hydraulic drive device for a hydraulic working machine that can perform the above.

(1) In order to achieve the above object, the present invention provides a hydraulic drive device for a hydraulic working machine including a swing body and a working device, which is driven by a hydraulic pump and pressure oil discharged from the hydraulic pump, A swing motor unit having a built-in hydraulic swing motor for rotating the swing body, a control valve including a swing direction control valve for controlling the flow of pressure oil supplied from the hydraulic pump to the hydraulic swing motor, and in the swing motor unit A first swing relief valve with a shockless function for limiting the drive pressure or braking pressure of the hydraulic swing motor so as not to exceed the first set pressure, and the drive pressure or brake pressure of the hydraulic swing motor is A second swing relief valve that limits the second set pressure lower than the first set pressure, and a relief characteristic of the first swing relief valve; A first relief mode that remains valid, and a second relief characteristic in which the first set pressure of the relief characteristic of the first swing relief valve is reduced to the second set pressure of the second swing relief valve. A selection device for selecting one of the relief modes is provided.

  In the present invention configured as described above, when the first relief mode is selected by the selection device, the relief characteristics of the first swing relief valve are enabled as they are, and the shockless function of the first swing relief valve is obtained. When the second relief mode is selected by the selection device, a relief characteristic is obtained by reducing the first set pressure of the relief characteristic of the first swing relief valve to the second set pressure of the second swing relief valve.

  As a result, in the first relief mode, as in the case of a relief valve having a conventional shockless function, it is possible to reduce a shock at the time of turning on or turning off. Further, in the second relief mode, the hydraulic swing motor is driven by setting the second set pressure of the second swing relief valve to a value between the relief start pressure of the first swing relief valve and the first set pressure. The pressure or braking pressure can be reduced and a shockless function can be obtained. As a result, the maximum drive torque or braking torque of the hydraulic swing motor can be reduced, and the shock at the time of turning start or stop can be reduced by the shockless function. Can be reduced.

As a result, it is possible to easily change the drive pressure or braking pressure of the hydraulic swing motor while maintaining the structure of the first swing relief valve having a shockless function, and to change the maximum drive torque or braking torque of the hydraulic swing motor. it can.
(2) In the hydraulic drive device for the hydraulic working machine according to (1), preferably, when the hydraulic swing motor performs a pumping action when the swing body is decelerated or stopped, the suction drive side of the hydraulic swing motor is A replenishment check valve that replenishes pressure oil from a discharge oil path downstream of the one swing relief valve, wherein the first swirl relief valve discharge oil is at a position near the downstream of the first swing relief valve; The downstream side of the second swing relief valve is connected to the drain oil passage on the downstream side of the first swing relief valve so as to merge with the discharged oil of the swing relief valve.

By connecting the downstream side of the second swing relief valve in this way and joining the discharged oil of the second swing relief valve with the discharged oil of the first swing relief valve at a position near the downstream of the first swing relief valve, the hydraulic pressure is increased. The supply of pressure oil by the replenishment check valve when the swing motor performs pumping is ensured, and the occurrence of cavitation of the hydraulic swing motor can be suppressed.
(3) In the hydraulic drive device of the hydraulic working machine according to (1) or (2), preferably, the second set pressure of the second swing relief valve is the relief start pressure of the first swing relief valve and the pressure It is set to a value between the first set pressure.

As a result, in the second relief mode, the driving pressure or braking pressure of the hydraulic swing motor can be reduced and a shockless function can be obtained.
(4) In the hydraulic drive device for a hydraulic working machine according to any one of (1) to (3), preferably, the second swing relief valve is disposed in an independent relief valve block, and the swing motor unit is The port of the pair of actuator oil passages connected to the hydraulic swing motor has a port surface that is open, and the relief valve block is assembled and integrated with the port surface of the swing motor unit.

Thereby, the change point from the conventional turning motor unit can be reduced, and the manufacturing cost can be reduced.
(5) In the hydraulic drive device for a hydraulic working machine according to any one of (1) to (3), preferably, the second swing relief valve is disposed in an independent relief valve block, and the control valve is The port of a pair of actuator oil passages connected to the turning direction control valve has a port surface that is open, and the relief valve block is assembled and integrated with the port surface of the control valve.

As a result, even if there is not enough space around the swing motor unit and the relief valve block cannot be assembled to the swing motor unit, the relief valve block can be assembled and integrated with the control valve to reduce piping. And it can be mounted on the car body compactly.
(6) In the hydraulic drive device for a hydraulic working machine according to any one of the above (1) to (3), and preferably, the selection device has a switching valve disposed on the upstream side of the second swing relief valve. Then, by selectively switching the switching valve between the communication position and the shut-off position, one of the first relief mode and the second relief mode is selected.

As a result, a selection device can be configured using a normal inexpensive relief valve as the second swing relief valve.
(7) In the hydraulic drive device for a hydraulic working machine according to any one of (1) to (3), and preferably, the selection device is provided in the second swing relief valve, A solenoid capable of changing the set pressure to the first set pressure and the second set pressure is provided, and one of the first relief mode and the second relief mode is selected by controlling the current flowing through the solenoid. To do.

  Thereby, a switching valve becomes unnecessary and the number of parts can be reduced.

  Also, three or more different relief pressures can be set, and a shockless function can be obtained at each set pressure, and the range of control can be expanded.

  According to the present invention, it is possible to easily change the driving pressure or the braking pressure of the hydraulic swing motor without using the relief valve for the swing motor having a complicated mechanism, without changing the structure of the relief valve having the shockless function. The maximum driving torque or braking torque of the hydraulic swing motor can be changed.

1 is a diagram showing a hydraulic drive device for a hydraulic working machine according to a first embodiment of the present invention. It is a figure which shows the relief pressure characteristic of the hydraulic drive device by the 1st Embodiment of this invention. It is a figure which shows the external appearance of the hydraulic shovel which is an example of the hydraulic working machine with which the hydraulic drive device of this invention is mounted. It is a figure which shows the hydraulic drive device of the hydraulic working machine by the 2nd Embodiment of this invention. It is a figure which shows the hydraulic drive device of the hydraulic working machine by the 3rd Embodiment of this invention. It is a figure which shows the hydraulic drive device of the hydraulic working machine by the 4th Embodiment of this invention. It is a figure which shows the hydraulic drive device of the hydraulic working machine by the 5th Embodiment of this invention. It is a figure which shows the relationship between the command electric current and relief pressure in the 5th Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
<First Embodiment>
FIG. 1 is a diagram illustrating a hydraulic drive device for a hydraulic working machine according to a first embodiment of the present invention.

  The hydraulic drive device is driven by a diesel engine 1 as a prime mover, a variable displacement hydraulic pump 2 driven by the engine 1, a hydraulic oil tank 3, and pressure oil discharged from the hydraulic pump 2, and a revolving body. A plurality of swivel motor units 4 incorporating a hydraulic swivel motor 40 that rotationally drives 101 (see FIG. 2) and a swivel direction control valve 50 that controls the flow of pressure oil supplied from the hydraulic pump 2 to the hydraulic swivel motor 40. A control valve 5 having a built-in directional control valve, an operation lever device 6 for instructing the operation of the swing body 101, a controller 7, a relief pressure change instruction switch 8, an oil cooler 9, and a back pressure valve 10. Yes.

  The control valve 5 has a valve housing 52, and a main spool 51 a of the turning direction control valve 50 is disposed in the valve housing 52. Pressure receiving portions 51b and 51c are provided at both ends of the main spool 51a, and the operating pilot pressure from the operating lever device 6 is guided to one of the pressure receiving portions 51b and 51c, and the turning direction control valve is switched by this operating pilot pressure. The In the housing 52, a pump oil passage 53, a pair of actuator oil passages 54a and 54b, and a discharge oil passage 55 are formed. When the main spool 51a of the turning direction control valve 50 is switched from the neutral position shown to the left or right shown in the drawing, the pressure oil from the hydraulic pump 2 is supplied to the pump oil passage 53, the turning direction control valve 50, and the pair. It is supplied to the turning motor unit 4 via one of the actuator oil passages 54a and 54b (for example, the actuator oil passage 54a). The return oil from the turning motor unit 4 is returned to the tank 3 via the other of the pair of actuator oil passages 54a and 54b (for example, the actuator oil passage 54b), the turning direction control valve 50, and the discharge oil passage 55.

  The turning direction control valve 50 is a center bypass type valve, and is arranged on the center bypass oil passage 56 connected to the pump oil passage 53 on the upstream side and connected to the discharge oil passage 55 on the downstream side. When the main spool 51a is in the neutral position shown in the figure, the turning direction control valve 50 opens the center bypass oil passage 56 and circulates the entire amount of oil discharged from the hydraulic pump 2 to the tank 3 via the discharge oil passage 55. . When the main spool 51a of the turning direction control valve 50 is switched from the neutral position shown in the drawing to either the right or left shown in the drawing, the center bypass oil passage 56 is squeezed according to the switching stroke, and the pressure in the pump oil passage 53 ( The discharge pressure of the hydraulic pump 2 is supplied to the swing motor unit 4 via the swing direction control valve 50 due to the increase in pressure. When the turning direction control valve 50 is switched at full stroke, the center bypass oil passage 56 is completely closed, and the entire amount of oil discharged from the hydraulic pump 2 is supplied to the turning motor unit 4.

  Other directional control valves (not shown) of the control valve 5 are configured in the same manner, and these directional control valves are arranged in series on the center bypass oil passage 56 as is well known.

  The swing motor unit 4 has a motor housing 41, and components (for example, a swash plate and a piston) of the hydraulic swing motor 40 are arranged in the housing 41. In the housing 41, a pair of actuator oil passages 42a and 42b and a discharge oil passage 43 are formed, and a pair of first swing relief valves 44a and 44b having a shockless function and a replenishment 1 A pair of check valves 45a and 45b, a pair of second swing relief valves 46a and 46b having no shockless function, and a pair of electromagnetic switching valves 47a and 47b are arranged.

  Each of the pair of first swing relief valves 44 a and 44 b has an upstream side connected to a pair of actuator oil passages 42 a 42 b and a downstream side (discharge side) connected to a discharge oil passage 43. The pair of first swing relief valves 44a and 44b has a function of limiting the pressure of the actuator oil passages 42a and 42b so as not to exceed the first set pressure.

  Here, the pressure of the actuator oil passages 42a and 42b limited by the first swing relief valves 44a and 44b is that the hydraulic swing motor 40 is supplied from the hydraulic pump 2 when the swing body 101 (see FIG. 2) is activated. When the revolving body 101 is driven by the pressurized oil, the driving pressure is the driving pressure. When the revolving body 101 is decelerated or stopped, the hydraulic revolving motor 40 is driven inertially by the revolving body 101 and the pump of the hydraulic revolving motor 40 is driven. When braking pressure (back pressure) is generated in the discharge-side actuator oil passage 42a or 42b due to the action, this is the braking pressure.

  The pair of replenishment check valves 45 a and 45 b has an upstream side connected to the pair of actuator oil passages 42 a and 42 b and a downstream side connected to the discharge oil passage 43. The replenishment check valves 45a and 45b are configured such that when the swing body is stopped, the hydraulic swing motor 40 is driven by inertia by the swing body 101, and the suction side actuator oil passage 42a or the hydraulic swing motor 40 is pumped by the hydraulic swing motor 40. When 42b is going to become a negative pressure, pressure oil is supplied to the actuator oil passage 42a or 42b from the discharge oil passage 43 on the downstream side of the first swing relief valves 44a and 44b to prevent the occurrence of cavitation. .

  The pair of second swing relief valves 46a, 46b is connected to the pair of actuator oil passages 42a, 42b on the upstream side, like the pair of first swing relief valves 44a, 44b, respectively, and downstream (discharge side). Is connected to the drain oil passage 43. In other words, the pair of second swing relief valves 46a, 46b are connected in parallel to the pair of actuator oil passages 42a, 42b with respect to the pair of first swing relief valves 44a, 44b, and the second swing relief valve. On the downstream side of the valves 46a, 46b, the oil discharged from the second swing relief valves 46a, 46b joins the oil discharged from the first swing relief valves 44a, 44b at a position near the downstream of the first swing relief valves 44a, 44b. In addition, it is connected to a drain oil passage 43 on the downstream side of the first swing relief valves 44a, 44b. The pair of second swing relief valves 46a and 46b prevent the pressure of the actuator oil passages 42a and 42b (drive pressure or braking pressure of the hydraulic swing motor 40) from exceeding a second set pressure lower than the first set pressure. It has a function to limit.

  The pair of electromagnetic switching valves 47a and 47b are disposed on the upstream side of the pair of second swing relief valves 46a and 46b, respectively. When the pair of electromagnetic switching valves 47a and 47b are in the illustrated closed position, communication between the pair of actuator oil passages 42a and 42b and the pair of second swing relief valves 46a and 46b is blocked. The functions of the second swing relief valves 46a and 46b are disabled. At this time, the pair of first swing relief valves 44a and 44b function independently, and the relief characteristics of the first swing relief valve are effective as they are. When the pair of electromagnetic switching valves 47a and 47b are switched from the illustrated closed position to the open position, the pair of actuator oil passages 42a and 42b communicate with the pair of second swing relief valves 46a and 46b. The function of the pair of second swing relief valves 46a and 46b is made effective. At this time, the pair of first swing relief valves 44a, 44b and the pair of second swing relief valves 46a, 46b function in combination, and the relief characteristics and the second swing of the first swing relief valves 44a, 44b. Relief characteristics in which the relief characteristics of the relief valves 46a and 46b are combined to reduce the first set pressure P1 of the relief characteristics of the first swing relief valves 44a and 44b to the second set pressure P2 of the second swing relief valves 46a and 46b. Is obtained (described later).

  Thus, by switching the opening / closing of the pair of electromagnetic switching valves 47a and 47b, the first relief mode in which the pair of first swing relief valves 44a and 44b function independently and the pair of first swing reliefs. Either one of the second relief modes in which the valves 44a and 44b and the pair of second swing relief valves 46a and 46b function in combination can be selected.

  The pair of actuator oil passages 54a and 54b in the control valve 5 and the pair of actuator oil passages 42a and 42b in the swing motor unit 4 are connected via a pair of actuator pipes 11a and 11b. A discharge oil passage 55 in the control valve 5 is connected to the first discharge pipe 12, a discharge oil passage 43 in the turning motor unit 4 is connected to the second discharge pipe 13, and the first and second discharge pipes 12. , 13 are connected to the tank 3 via a common third discharge conduit 14. The oil cooler 9 and the back pressure valve 10 are disposed in the third discharge conduit 14.

  The electromagnetic switching valves 47 a and 47 b are switched by a signal from the controller 7. The controller 7 receives an instruction signal from the relief pressure change instruction switch 8, and outputs a switching signal to the electromagnetic switching valves 47a and 47b when the instruction signal instructs to change the relief pressure.

  The controller 7, the relief pressure change instruction switch 8, and the electromagnetic switching valves 47a and 47b are provided in the first relief mode in which the relief characteristics of the first swing relief valves 44a and 44b are made valid as they are, and the relief of the first swing relief valves 44a and 44b. A selection device is provided that selects one of the second relief modes in which the relief characteristic is obtained by reducing the first set pressure of the characteristic to the second set pressure of the second swing relief valves 46a and 46b.

  FIG. 2 is a diagram showing an external appearance of a hydraulic excavator equipped with the hydraulic drive device shown in FIG.

  The hydraulic excavator includes a traveling body 100, a revolving body 101, and a front work machine 102. The traveling body 100 drives left and right crawlers 100a and 100b (only one shown) by left and right traveling motors 110a and 110b (only one shown). The swivel body 101 is swung on the travel body 100 by the hydraulic swivel motor 40. The front work machine 102 has an articulated structure including a boom 103, an arm 104, and a bucket 105, and is driven to rotate in a vertical plane by a boom cylinder 111, an arm cylinder 112, and a bucket cylinder 113, respectively. A suspension hook 106 is provided on the bucket 105, and the suspension work can be performed by suspending the load W on the suspension hook 106.

  The drive of the travel left motor 110a is controlled by the travel left direction control valve, the drive of the travel right motor 110b is controlled by the travel right direction control valve, and the drive of the hydraulic turning motor 40 is controlled by the turning direction control valve 50, The driving of the boom cylinder 111 is controlled by a boom direction control valve, the driving of the arm cylinder 112 is controlled by an arm direction control valve, and the driving of the bucket cylinder 113 is controlled by a bucket direction control valve. In FIG. 1, directional control valves other than the turning directional control valve 50 are not shown.

  FIG. 3 is a diagram showing a change in the relief pressure when the pressure in the actuator oil passages 42a and 42b increases. The horizontal axis represents time, and the vertical axis represents the turning relief pressure. A is the relief characteristic of the first swing relief valves 44a and 44b, B is the relief characteristic of the second swing relief valves 46a and 46b, P1 is the first set pressure of the relief relief characteristic A of the first swing relief valves 44a and 44b, P2 Is the second set pressure of the relief characteristic B of the second swing relief valves 46a, 46b, A1 is the characteristic of the shockless function of the first swing relief valves 44a, 44b, and P0 is the first swing relief valve 44a, 44b. The relief start pressure in the shockless function is shown.

The shockless function refers to starting valve opening at a pressure P0 that is intentionally lower than the set pressure P1, as indicated by A1 in the relief characteristics A of the first swing relief valves 44a and 44b.
It refers to the function of reducing the impact of pressure rise even when the driving pressure or braking pressure is suddenly generated.

  The second set pressure P2 of the second swing relief valves 46a, 46b is set to a value between the relief start pressure P0 and the first set pressure P1 of the shockless function of the first swing relief valves 44a, 44b. The first set pressure P1 of the first swing relief valves 44a, 44b is, for example, 30 Mpa, the relief start pressure P0 of the shockless function of the first swing relief valves 44a, 44b is, for example, 20 Mpa, and the second swing relief valves 46a, The second set pressure P2 of 46b is 26 Mpa, for example.

  When the relief pressure change instruction switch 8 does not instruct the change of the relief pressure, the electromagnetic switching valves 47a and 47b are in the illustrated closed position, and the first pair of first swing relief valves 44a and 44b function independently. Relief mode is selected. At this time, the relief characteristics of the first swing relief valves 44a and 44b are effective as they are, and the relief pressure when the pressure of the actuator oil passage 42a or 42b rises changes as shown by the characteristic A. With this characteristic, when the pressure in the actuator oil passage 42a or 42b exceeds P0, a shockless function is obtained with the characteristic A1.

  When the relief pressure change instructing switch 8 instructs to change the relief pressure, the controller 7 outputs a command signal to the electromagnetic switching valves 47a and 47b, and the electromagnetic switching valves 47a and 47b are switched from the closed position to the open position. The pressure oil passage to the swing relief valves 46a and 46b is opened. At this time, the second relief mode in which the first turning relief valves 44a and 44b and the second turning relief valves 46a and 46b function in combination is selected, and the relief pressure when the pressure in the actuator oil passage 42a or 42b rises is a characteristic. It changes like B. That is, the relief characteristics of the first swing relief valves 44a, 44b and the relief characteristics of the second swing relief valves 46a, 46b are combined, and the first set pressure P1 of the relief characteristics of the first swing relief valves 44a, 44b is second swung. The relief characteristic reduced to the second set pressure P2 of the relief valves 46a and 46b is obtained.

  In the second relief mode, the first swing relief valves 44a and 44b and the second swing relief valves 46a and 46b function in combination, so that the relief pressure is the first swing relief valves 44a and 44b during the period (a). Is controlled by the pressure determined by the shockless mechanism A1, and the time zone (b) is controlled to the second set pressure P2 determined by the second swing relief valves 46a and 46b.

  The pressure oil relieved by the first and second turning relief valves 44a or 44b, 46a or 46b passes through the discharge oil passage 43 in the turning motor unit 4 and passes through the external discharge pipes 13 and 14 to control the direction. The oil returns from the valve 51, passes through the oil cooler 9 and the back pressure valve 10, and returns to the hydraulic oil tank 3.

  In the present embodiment configured as described above, when the first relief mode is selected by operating the relief pressure change instruction switch 8, the relief characteristics of the first swing relief valves 44a and 44b become effective as they are. The shockless function of the swing relief valves 44a and 44b is obtained. When the second relief mode is selected by operating the relief pressure change instruction switch 8, the first setting pressure P1 of the relief characteristics of the first swing relief valves 44a and 44b is set to the second setting of the second swing relief valves 46a and 46b. The relief characteristic lowered to the pressure P2 is obtained.

  As a result, in the first relief mode, as in the case of a relief valve having a conventional shockless function, it is possible to reduce a shock at the time of turning on or turning off. In the second relief mode, the second set pressure P2 of the second swing relief valves 46a and 46b is set to a value between the relief start pressure P0 and the first set pressure P1 of the first swing relief valves 44a and 44b. Therefore, the driving pressure or braking pressure of the hydraulic turning motor 40 can be reduced and a shockless function can be obtained. As a result, the maximum driving torque or braking torque of the hydraulic turning motor 40 can be reduced and shockless. The function can reduce the shock when turning or stopping turning.

  As a result, the drive pressure or braking pressure of the hydraulic swing motor 40 can be easily changed without changing the structure of the first swing relief valves 44a and 44b having a shockless function, and the maximum drive torque or braking torque of the hydraulic swing motor 40 can be changed. Can be changed.

  Further, since the downstream side of the second swing relief valves 46a, 46b is connected to the discharge oil passage 43, the oil discharged from the second swing relief valves 46a, 46b is located in the vicinity of the downstream of the first swing relief valves 44a, 44b. And merges with the oil discharged from the first swing relief valves 44a and 44b. This makes it possible to reliably supply the pressure oil by the replenishment check valves 45a and 45b when the hydraulic swing motor 40 performs a pump action, and suppress the occurrence of cavitation in the hydraulic swing motor 40 and the actuator oil passages 42a and 42b. be able to.

  Next, an application example of this embodiment will be described.

1. Application to suspended load mode (crane mode) There is a suspended load operation (crane operation) as an operation performed by a hydraulic excavator. As shown in FIG. 2, this is an operation of suspending and moving the load W on the suspension hook 106 provided on the bucket 105. When performing such a suspended work, the suspended load mode is selected by turning on the mode switch for setting the suspended load mode, and the operating speed of the actuator such as the hydraulic turning motor 40 is reduced by reducing the rotational speed of the engine 1 in advance. Etc. are kept low, thereby suppressing the occurrence of vibration (load swing) of the suspended load.

  When this embodiment is applied to the suspended load mode, the first relief mode is used as the normal mode, and the second relief mode is used as the suspended load mode. Further, the first set pressure P1 of the first swing relief valves 44a and 44b is set to a pressure suitable for normal work (for example, 30 Mpa described above), and the second set pressure P2 of the second swing relief valves 46a and 46b is suspended. A pressure suitable for the mode (for example, 26 MPa described above) is set.

  When performing normal work, the relief pressure change instruction switch 8 is turned OFF to select the first relief mode. At this time, the electromagnetic switching valves 47a and 47b are in the closed position shown in the figure, and the pair of first swing relief valves 44a and 44b function independently, and the relief pressure when the pressure in the actuator oil passage 42a or 42b rises is characteristic. It changes like A. With this characteristic, when the pressure in the actuator oil passage 42a or 42b exceeds P0, a shockless function is obtained with the characteristic A1, thereby reducing a shock at the time of turning start or stop.

  When performing a suspended work, the relief pressure change instruction switch 8 is switched to ON to select the second relief mode. At this time, the electromagnetic switching valves 47a and 47b are switched from the closed position to the open position, and the first swing relief valves 44a and 44b and the second swing relief valves 46a and 46b function in combination, and the actuator oil passage 42a or 42b. The relief pressure when the pressure rises changes like a relief characteristic B in which the first set pressure P1 of the relief characteristic A is reduced to the second set pressure P2 of the second swing relief valves 46a and 46b. With this characteristic, if the pressure in the actuator oil passage 42a or 42b exceeds P0, a shockless function is obtained with the characteristic A1, and the drive pressure of the hydraulic swing motor 40 decreases from P1 to P2, so the hydraulic swing motor 40 The maximum driving torque or braking torque is also reduced. Accordingly, the shock at the time of turning start or stop can be reduced by the shockless function, and the maximum driving torque or the braking torque of the hydraulic turning motor 40 is reduced, so that the turning acceleration or turning deceleration is reduced, and the load is reduced. Less hanging work can be done.

  The relief pressure change instruction switch 8 may be provided separately from the mode switch for setting the suspended load mode, or may be used as a mode switch.

2. Application to change of front attachment The hydraulic excavator can perform not only the bucket 105 as shown in FIG. 2 as the front attachment but also various work other than the normal work by exchanging the bucket with another attachment. . For example, when the bucket 105 is changed to a crusher, a crushing operation at a dismantling site can be performed. By the way, when the weights of the bucket 105 and other attachments are compared, the other attachments are often heavier than the bucket 105. Normally, the set pressure of the swing relief valve is set to a pressure suitable for driving the swing body to swing when the attachment is a bucket. Therefore, when the attachment is replaced with an attachment other than the bucket, the turning load of the turning body increases. Therefore, when the set pressure of the turning relief valve is left as it is, the driving pressure or braking pressure of the hydraulic turning motor 40 is too low, In some cases, the turning motion becomes slow.

When applying this embodiment to the change of the front attachment,
The second relief mode is used when the attachment is a bucket 105, and the first relief mode is used when the attachment is an attachment other than a bucket. Further, the second set pressure P2 of the second swing relief valves 46a, 46b is set to a pressure suitable for the case where the front attachment is the bucket 105 (for example, 30 MPa), and the first set pressure of the first swing relief valves 44a, 44b is set. P1 is set to a pressure (for example, 32 MPa) suitable for an attachment (for example, a crusher) other than the bucket.

  When the bucket 105 is used as an attachment, the relief pressure change instruction switch 8 is switched to ON to select the second mode. Thus, the first swing relief valves 44a and 44b and the second swing relief valves 46a and 46b function in combination, and the first set pressure P1 of the relief characteristic A is changed to the second set pressure P2 of the second swing relief valves 46a and 46b. A relief characteristic B that is reduced to a low level is obtained. With this characteristic, a shockless function can be obtained, and a pressure P2 suitable for the case where the front attachment is the bucket 105 is obtained as the driving pressure of the hydraulic turning motor 40. Therefore, shock at the time of turning start or turning stop can be reduced. At the same time, when the attachment is the bucket 105, the optimum turning acceleration or turning deceleration can be obtained, and turning operation with good operability can be performed.

  When using an attachment other than a bucket, for example, a crusher, the relief pressure change instruction switch 8 is turned OFF and the first relief mode is selected. Accordingly, the pair of first swing relief valves 44a and 44b function independently, and the relief characteristic A is obtained. With this characteristic, a shockless function can be obtained, and a pressure P1 suitable for the case where the front attachment is a crusher can be obtained as the driving pressure of the hydraulic turning motor 40, so that the shock at the time of turning start or stop can be reduced. At the same time, when the attachment is a crusher, the optimum turning acceleration or turning deceleration can be obtained. In this case, a turning operation with good operability can be performed.

3. Application to control requiring change of turning drive torque Although not shown, it may be necessary to change the turning drive torque (or braking torque) in conjunction with some control. In that case, a control unit for performing such control may be provided instead of the relief pressure change instruction switch 8, and a change of the relief pressure may be instructed by a control signal from the control unit to switch the setting of the swing relief pressure. . As a result, the turning drive torque (or braking torque) is switched in conjunction with the control, and effects such as improved turning operability can be obtained.
<Second Embodiment>
FIG. 4 is a diagram showing a hydraulic drive device for a hydraulic working machine according to a second embodiment of the present invention. In the figure, members equivalent to those shown in FIG.

  In FIG. 4, the swing motor unit 4A includes a swing motor section 4-1 and an additional relief valve section 4-2.

  In the swing motor section 4-1, the hydraulic swing motor 40 is disposed in the housing 41-1, and a pair of actuator oil passages 42a-1, 42b-1 and a discharge oil passage 43-1 are formed. A pair of first swing relief valves 44a and 44b with a shockless function and a pair of check valves 45a and 45b for replenishment are arranged.

  Further, the housing 41-1 includes a first port surface 63 in which the ports 61a and 61b of the pair of actuator oil passages 42a-1 and 42b-1 and the port 62 on one end side of the discharge oil passage 43-1 open, and a discharge. It has the 2nd port surface 65 which the port 64 of the other end side of the oil path 43 opens. The discharge oil passage 43 is connected to the second discharge pipe 13 through the port 64.

  The additional relief valve section 4-2 is configured as a relief valve block in which the housing 41-2 is independent from the housing 41-1 of the swing motor section 4-1. Hereinafter, the additional relief valve section 4-2 is referred to as a relief valve block. The relief valve block 4-2 is assembled with the swing motor section 4-1 by assembling the housing 41-2 to the first port surface 63 of the housing 41-1 of the swing motor section 4-1, for example, by fixing with a bolt. It is integrated.

  The relief valve block 4-2 is a pair of actuator oil passages 42a-2, 42b-2 and a discharge oil passage 43-2 formed in the housing 41-2 and having no shockless function. The second swing relief valves 46a, 46b and a pair of electromagnetic switching valves 47a, 47b are arranged.

  In the state where the swing motor section 4-1 and the relief valve block 4-2 are integrated, the actuator oil passages 42a-2 and 42b-2 of the relief valve block 4-2 are connected to the actuator oil passage 42a-1 of the swing motor section. , 42b-1 and the drain oil passage 43-2 communicates with the drain oil passage 43-1. The actuator oil passages 42a-2 and 42b-2 of the relief valve block 4-2 are connected to a pair of actuator oil passages 54a and 54b in the control valve 5 via a pair of actuator conduits 11a and 11b. .

  Also in this embodiment, the same effect as that of the first embodiment can be obtained.

In the case of the first embodiment, the swing motor unit 4 includes the second swing relief valves 46a and 46b and the electromagnetic switching valves 47a and 47b as a unit. Occur frequently. On the other hand, in this embodiment, the relief valve block 4-2 is combined with the swing motor section 4-1 having a structure in which the port of the discharge oil passage 43-1 is opened with respect to the conventional swing motor unit. Since the configuration is adopted, changes from the conventional swing motor unit can be reduced and the manufacturing cost can be reduced.
<Third Embodiment>
FIG. 5 is a diagram showing a hydraulic drive device for a hydraulic working machine according to a third embodiment of the present invention. In the figure, members equivalent to those shown in FIGS. 1 and 4 are denoted by the same reference numerals.

  In FIG. 5, the swing motor unit 4B is composed of a swing motor section 4-1B and an additional relief valve section 4-2B, and the additional relief valve section 4-2B is a housing 41-2 which is a housing of the swing motor section 4-1. It is configured as a relief valve block independent of 41-1 and swivels by assembling the housing 41-2 to the first port surface 63 of the housing 41-1 of the swivel motor section 4-1B by fixing it with a bolt or the like. The point integrated with the motor section 4-1B is the same as that of the second embodiment.

  In the present embodiment, the port of the discharge oil passage 43-1B is not opened in the first port surface 63 of the housing 41-1 of the swing motor section 4-1B, and the swing motor section 4-1B is a conventional swing motor. It is configured the same as the unit.

  The drain oil passage 43-2B of the relief valve block 4-2B has a port 71 that opens at a third port surface 70 provided on one side surface of the housing 41-2 of the relief valve block 4-2B. Is connected to the second discharge pipe 13 via the fourth discharge pipe 72 at a position 73 in the vicinity of the second port surface 65 where the port 64 of the discharge oil path 43-1B of the swing motor section 4-1B opens. Has been. The position 73 in the vicinity of the second port surface 65 is, for example, a position away from the second port surface 65 by 0 to 20 cm, more preferably about 0 to 10 cm. As a result, on the downstream side of the second swing relief valves 46a and 46b, the oil discharged from the second swing relief valves 46a and 46b is located at a position 73 near the downstream of the first swing relief valves 44a and 44b. The exhaust oil passage 43-1B on the downstream side of the first swing relief valves 44a and 44b is connected so as to merge with the discharged oil.

  In the second embodiment, the relief motor block 4-1 is assembled to the swing motor section 4-1, but the drain oil passage 43-2 in the relief valve block 4-2 is connected to the swing motor section 4. -1 is connected to the drain oil passage 43-1 of the swing motor section 4-1, so that the port of the drain oil passage 43-1 is the first port in the swing motor section 4-1. It is necessary to open the surface 63.

  On the other hand, in the present embodiment, the point that the relief valve block 4-2B is assembled to the swing motor section 4-1B is the same as the second embodiment, but the second swing relief valve 46a, The port 71 of the discharge oil passage 43-2B on the downstream side of 46b is opened at the third port surface 70 of the housing 41-2 of the relief valve block 4-2B, and the port 71 is swung through the fourth discharge pipe 72. At a position 73 near the second port surface 65 of the motor section 4-1 B, the oil discharged from the second swing relief valves 46 a and 46 b is downstream of the first swing relief valves 44 a and 44 b. The oil is discharged from the first turning relief valves 44a and 44b at a position 73 in the vicinity.

  With this configuration, the swing motor section 4-1B has the same configuration as the conventional swing motor unit, and the number of changes from the conventional swing motor unit can be further reduced, and the manufacturing cost can be further reduced.

Further, on the downstream side of the second swing relief valves 46a and 46b, the first swing relief valves 44a and 44b are disposed at a position 73 in the vicinity of the downstream of the first swing relief valves 44a and 44b. As in the first and second embodiments, the supply of pressure oil by the replenishment check valves 45a and 45b when the hydraulic swing motor 40 performs a pumping operation is ensured, as in the first and second embodiments. It is possible to suppress the occurrence of cavitation in the actuator oil passages 42a-2 and 42b-2.
<Fourth embodiment>
FIG. 6 is a diagram illustrating a hydraulic drive device for a hydraulic working machine according to a fourth embodiment of the present invention. In the figure, members equivalent to those shown in FIGS. 1, 4 and 5 are denoted by the same reference numerals.

  In FIG. 6, the swing motor unit 4C-1 comprises only the swing motor section 4-1B in the third embodiment, and the relief valve block 4C-2 is independent of the swing motor section 4-1B and is a swing motor section. It is constituted by an additional relief valve section 4-2B separated from 4-1B.

  The valve housing 52 of the control valve 5 has a fourth port surface 75 in which the ports 74a and 74b of the pair of actuator oil passages 54a and 54b are opened, and the relief valve block 4C-2 is the fourth port surface of the control valve 5. It is integrated with the control valve 5 by being attached to 75 by fixing with a bolt or the like. In a state where the relief valve block 4C-2 and the control valve 5 are integrated, the actuator oil passages 42a-2 and 42b-2 of the relief valve block 4C-2 communicate with the actuator oil passages 54a and 54b of the control valve 5. The actuator oil passages 42a-2 and 42b-2 of the relief valve block 4C-2 are connected to the actuator oil passages 42a-1 and 42b-1 in the swing motor unit 4C-1 and a pair of actuator conduits 11a and 11b. Connected.

  Further, the drain oil passage 43-2B of the relief valve block 4C-2 has a first port 64 of the drain oil passage 43-1B of the turning motor unit 4C-1 opened through the port 71 and the fifth discharge pipe 76. The second discharge pipe 13 is connected at a position 73 near the two-port surface 65. As a result, on the downstream side of the second swing relief valves 46a and 46b, the oil discharged from the second swing relief valves 46a and 46b is located at a position 73 near the downstream of the first swing relief valves 44a and 44b. The exhaust oil passage 43-1B on the downstream side of the first swing relief valves 44a and 44b is connected so as to merge with the discharged oil.

  Depending on the machine (hydraulic excavator), there is not enough space around the swing motor unit 4C-1, and the relief valve block 4C-2 may not be assembled to the swing motor unit 4C-1. In that case, the relief valve block 4C-2 is arranged between the swing motor unit 4C-1 and the control valve 5. In this case, the relief valve block 4C-2 and the swing motor unit 4C-1 are arranged. In addition, a place for providing piping between the relief valve block 4C-2 and the control valve 5 and fixing the relief valve block 4C-2 is required.

  On the other hand, in the present embodiment, the relief valve block 4C-2 is assembled and integrated with the control valve 5, so that the number of pipes can be reduced and the vehicle body can be mounted compactly.

Also in this case, the oil discharged from the second swing relief valves 46a and 46b of the relief valve block 4C-2 is discharged to the first swing relief valve 44a at a position 73 near the downstream of the first swing relief valves 44a and 44b. , 44b is combined with the discharged oil, so that, as in the first to third embodiments, the replenishment check valves 45a, 45b ensure the replenishment of the pressure oil when the hydraulic swing motor 40 performs the pumping action. The occurrence of cavitation in the actuator oil passages 42a-2 and 42b-2 can be suppressed.
<Fifth embodiment>
FIG. 7 is a view showing a hydraulic drive device for a hydraulic working machine according to a fifth embodiment of the present invention. In the figure, members equivalent to those shown in FIGS. 1 and 4 are denoted by the same reference numerals.

  In FIG. 7, the swing motor unit 4D includes a swing motor section 4-1 and a relief valve section 4-2D. In the second embodiment shown in FIG. 4, the relief valve section 4-2D includes a pair of second swing relief valves 46a and 46b that do not have a shockless function in the relief valve section 4-2 and a pair of electromagnetic switching valves 47a. , 47b are replaced with a pair of swing variable relief valves 81a, 81b. The pair of swing variable relief valves 81a and 81b have solenoids 82a and 82b, respectively, and a command current is supplied from the controller 7D to the solenoids 82a and 82b.

  FIG. 8 is a diagram showing the relationship between the command current and the relief pressure. The horizontal axis indicates the command current, and the vertical axis indicates the turning relief pressure. P1 is the first set pressure, P2 is the second set pressure, C1 is the command current when the relief pressure change instruction switch 8 is OFF (when the first relief mode is selected), and C2 is when the relief pressure change instruction switch 8 is ON (first Command current when 2 relief mode is selected.

  The swing variable relief valves 81a and 81b are configured to change the relief pressure from the first set pressure P1 to the second set pressure P2 by a command current from the controller 7D. When the relief pressure change instruction switch 8 is OFF (when the first relief mode is selected), the controller 7D supplies the command current C1 to the solenoids 82a and 82b, and the relief pressure of the first set pressure P1 is set. When the relief pressure change instruction switch 8 is switched to ON (when the second relief mode is selected), the controller 7D supplies the command current C2 to the solenoids 82a and 82b, and the relief pressure of the second set pressure P2 Is set.

  Also in the present embodiment configured as described above, when the relief pressure change instruction switch 8 is OFF, the relief characteristics of the first swing relief valves 44a and 44b are still valid (first relief mode), and the relief pressure change instruction When the switch 8 is switched to ON, the first set pressure of the relief characteristics of the first swing relief valves 44a and 44b is reduced to the second set pressure P2 of the P1 swing variable relief valves 81a and 81b (second swing relief valve). The relief characteristics thus obtained are obtained (second relief mode). As a result, the present embodiment can provide the same effects as those of the first and second embodiments.

  Further, the pair of switching valves 47a and 47b is not necessary, and the number of parts can be reduced.

  Further, in the case of the swing variable relief valves 81a and 81b, the command current supplied to the solenoids 82a and 82b is changed between C3 and C4 in FIG. 8 so as to be arbitrary between the first and second set pressures P1 and P2. The relief pressure can be set. Therefore, instead of the relief pressure change instruction switch 8, for example, a dial type setting device is provided, and an instruction signal corresponding to the rotational position of the dial type setting device is output to the controller 7D, and the controller 7D according to the instruction signal, By supplying a plurality of different command currents between C3 and C4 in FIG. 8 to the solenoids 82a and 82b, three or more different relief pressures are set, and a shockless function is obtained at each set pressure. And the range of control can be expanded.

  Furthermore, a control signal is input to the controller 7D, and a command current that changes steplessly in the controller 7D is supplied to the solenoids 82a and 82b, so that the relief pressure can be changed steplessly. In this case, for example, the attitude of the front work machine 102 (FIG. 2) (for example, the angle of the boom 103) is detected, and this angle signal is input to the controller 7D as a control signal, thereby The maximum driving torque or the braking torque of the hydraulic swing motor 40 can be changed in accordance with the change in the inertial mass of the upper swing body that changes according to the above, and the deterioration of operability can be improved.

DESCRIPTION OF SYMBOLS 1 Engine 2 Hydraulic pump 3 Hydraulic oil tank 4 Swing motor unit 5 Control valve 6 Operation lever apparatus 7 Controller 8 Relief pressure change instruction switch 9 Oil cooler 10 Back pressure valves 11a and 11b A pair of actuator lines 12 A first discharge line 13 Second exhaust conduit 14 Third exhaust conduit 40 Hydraulic swing motor 41 Motor housings 42a, 42b A pair of actuator oil passages 42a, 42b
43 Exhaust oil passages 44a, 44b First swivel relief valves 45a, 45b with shockless function A pair of check valves 46a, 46b for replenishment A pair of second swivel relief valves 47a, 47b without shockless function Electromagnetic switching valve 50 Swing direction control valve 51a Main spool 51b, 51c Pressure receiving portion 52 Valve housing 53 Pump oil passages 54a, 54b A pair of actuator oil passages 55 Drain oil passages 56 Center bypass oil passages 61a, 61b Port 62 Port 63 First Port surface 64 Port 65 Second port surface 70 Third port surface 71 Port 72 Fourth discharge pipe 73 Positions 74a, 74b in the vicinity of the second port face 65 Port 75 Fourth port face 76 Fifth discharge pipes 81a, 81b A pair of swing variable relief valves 82a and 82b Solenoid 100 Running body 101 Swing body 1 2 Front work machine 103 Boom 104 Arm 105 Bucket P1 First set pressure P2 Second set pressure P0 Relief start pressure A Relief characteristic of first swing relief valve 44a, 44b A1 Shockless function characteristic B Second swing relief valve 46a, 46b relief characteristics C1-C4 command current

Claims (7)

In the hydraulic drive device of the hydraulic working machine provided with the swivel body and the working device,
A hydraulic pump;
A swing motor unit that is driven by pressure oil discharged from the hydraulic pump and includes a hydraulic swing motor that rotates the swing body;
A control valve including a turning direction control valve for controlling a flow of pressure oil supplied from the hydraulic pump to the hydraulic turning motor;
A first swing relief valve with a shockless function that is disposed in the swing motor unit and limits the drive pressure or braking pressure of the hydraulic swing motor so as not to exceed a first set pressure;
A second swing relief valve that limits the drive pressure or braking pressure of the hydraulic swing motor so as not to exceed a second set pressure lower than the first set pressure;
A first relief mode in which the relief characteristic of the first swing relief valve is enabled as it is, and the first set pressure of the relief characteristic of the first swing relief valve is reduced to the second set pressure of the second swing relief valve A hydraulic drive device for a hydraulic working machine, comprising: a selection device that selects any one of the second relief modes in which the relief characteristics obtained are obtained. The hydraulic drive device for a hydraulic working machine according to claim 1,
When the hydraulic swing motor performs a pumping action when the swing body is decelerated or stopped, a replenishment check is performed to supply pressure oil to the suction side of the hydraulic swing motor from the discharge oil passage on the downstream side of the first swing relief valve. A valve,
The downstream side of the second swing relief valve is disposed on the downstream side of the second swing relief valve so that the oil discharged from the second swing relief valve merges with the oil discharged from the first swing relief valve at a position near the downstream of the first swing relief valve. 1. A hydraulic drive device for a hydraulic working machine, wherein the hydraulic drive unit is connected to the drain oil passage downstream of a one-turn relief valve. In the hydraulic drive device of the hydraulic working machine according to claim 1 or 2,
The hydraulic pressure of the hydraulic working machine, wherein the second set pressure of the second swing relief valve is set to a value between the relief start pressure of the first swing relief valve and the first set pressure. Drive device. In the hydraulic drive device of the hydraulic working machine according to any one of claims 1 to 3,
The second swing relief valve is disposed in an independent relief valve block;
The swing motor unit has a port surface in which a port of a pair of actuator oil passages connected to the hydraulic swing motor opens.
A hydraulic drive device for a hydraulic working machine, wherein the relief valve block is assembled and integrated with the port surface of the swing motor unit. In the hydraulic drive device of the hydraulic working machine according to any one of claims 1 to 3,
The second swing relief valve is disposed in an independent relief valve block;
The control valve has a port surface in which a port of a pair of actuator oil passages connected to the turning direction control valve is opened,
A hydraulic drive device for a hydraulic working machine, wherein the relief valve block is assembled and integrated with the port surface of the control valve. In the hydraulic drive device of the hydraulic working machine according to any one of claims 1 to 3,
The selection device includes a switching valve disposed on the upstream side of the second swing relief valve. By selectively switching the switching valve between a communication position and a cutoff position, the first relief mode and the first A hydraulic drive device for a hydraulic working machine, wherein one of two relief modes is selected. In the hydraulic drive device of the hydraulic working machine according to any one of claims 1 to 3,
The selection device includes a solenoid provided in the second swing relief valve and capable of changing a set pressure of the second swing relief valve to the first set pressure and the second set pressure, and flows to the solenoid. A hydraulic drive device for a hydraulic working machine, wherein one of the first relief mode and the second relief mode is selected by controlling an electric current.

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